A BGA (ball grid arrayed) semiconductor device provides a semiconductor chip disposed therein with sufficient I/O connections in response to highly performing semiconductor devices desired for use with electronic products. However, such a conventional BGA semiconductor device has the following drawbacks.
First, the conventional BGA semiconductor device has its overall height to be the sum of heights including a portion of an encapsulant higher than the chip, the chip, a substrate mounted with the chip, and solder balls implanted on a bottom surface of the substrate. In other words, such a structure makes the BGA semiconductor device hard to be miniaturized in profile, unless the foregoing components of the BGA semiconductor device are individually reduced in dimension. This therefore restricts the application of the BGA semiconductor device for use in a low-profile product.
Second, in the BGA semiconductor device, the chip is bonded to the substrate by means of an adhesive. Due to a great difference in coefficient of thermal expansion between the chip and the substrate, during a temperature cycle in subsequent fabricating processes or practical operation, thermal stress is generated and leads to delamination occurring at a bonding interface between the chip and the substrate. This greatly affects quality and reliability of fabricated products.
Moreover, after mounting the chip on the substrate via the adhesive such as silver paste, in order to stabilize the adhesive for firmly bonding the semiconductor to the substrate, an additional curing process is often performed for the adhesive. This not only increases the fabrication cost, but makes the fabrication time not able to be further reduced.
Further, for the solder balls implanted in the BGA semiconductor device, due to dimensional inaccuracy of the solder balls, or the occurrence of warpage in the substrate resulted from the thermal stress, the solder balls implanted on the substrate can not be positioned in satisfactory coplanarity. This therefore detrimentally affects electrical connection established between the solder balls and the external devices such as a printed circuit board by using surface mounted technology (SMT).